Internet Protocol (IP) technology is designed to enable packet-switched interconnection of a heterogeneous set of devices and communication networks. A potentially diverse set of network and link layer technologies are interconnected through nodes, e.g., gateways (or routers), that provide a packet forwarding service. Information is transferred between source and destination devices as blocks of data called datagrams, where the source and destination devices are identified by fixed length addresses. Routing in IP internetworks is connectionless in nature, in that datagrams are forwarded by routers on a hop-by-hop basis using the destination address in the datagram.
Mobile IP (or IP mobility) is an Internet Engineering Task Force (IETF) standard communications protocol that is designed to allow mobile devices to move from one network to another while maintaining a permanent IP address. The Mobile IP protocol allows location-independent routing of IP datagrams on the Internet. Each mobile device is identified by its home IP address regardless of its current location in the Internet. While roaming away from its home network, the mobile device is associated with a mobile IP address which identifies its current location. The mobile IP address for the mobile device may change or stay the same as the mobile device roams within the same or different networks. The Mobile IP protocol specifies how the mobile device registers with its home agent (in the home network) using its mobile IP address and how the home agent routes datagrams to the mobile device. A tunnel is established between the home agent for the home network and a foreign agent for the visited network. When a datagram addressed to the home IP address of the mobile device is received at the home network, the home agent forwards the datagram to the foreign agent in the visited network via the established tunnel.
The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. DNS serves to translate domain names that are meaningful to humans into numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative domain name servers, also known as dynamic DNS servers, for each domain. Domain name servers, also known as DNS servers, translate between a domain name (e.g., www.abc.com) and its corresponding IP address (e.g., 123.456.789.001). When setting up a call or session from a mobile or wireless device having a mobile IP (MIP) address, DNS server entries may be provided by a serving home and/or foreign agent which indicates which domain name server may be used by the mobile device for purposes of domain name resolution. For instance, when a MIP registration request is initiated by the mobile device, it may receive one or more DNS server entries from the foreign agent or by its home agent indicating which domain name servers may be used by the mobile device. The home agent may provide a DNS server in or proximate the home network while the foreign agent may provide a local DNS server (i.e., within the serving or visited network).
This DNS distribution scheme was developed primarily for wired networks but is finding applicability in wireless networks. However, unlike wired networks, wireless networks are more susceptible to corruption of data during over-the-air transmissions. Thus, a mobile device operating on a wireless network may receive incorrect, invalid, and/or corrupted DNS information. For time-sensitive applications (e.g., voice-over-IP, etc.), testing or contacting a DNS server to determine whether the received information is accurate, valid, or corrupt would tend to cause noticeable delays in providing service.
Consequently, a method is needed that facilitates DNS server updates in mobile devices operating on a wireless network while reducing or minimizing the potential delays of service.